Potential Nociceptive Role of the Thoracolumbar Fascia: A Scope Review Involving In Vivo and Ex Vivo Studies

Ultrasound-guided quadratus lumborum block in sheep: A cadaveric study

This prospective anatomical study aimed to establish an ultrasound-guided technique to the quadratus lumborum (QL) plane in sheep cadavers. Thirteen cadavers, weighing less than 117 kg, were included. In phase 1, one cadaver underwent dissection and two cadavers underwent 3D computed tomographic reconstruction for anatomical evaluation of the thoracolumbar region. In phase 2, two cadavers were used to compare two ultrasound techniques to the QL plane: lateral to the QL muscle with a transversal approach (LQL) and transmuscular between QL and psoas muscles with a longitudinal approach (TQL). For LQL, the reference was the first lumbar transverse process, whereas for TQL, it was the intertransverse region between the first and second lumbar vertebrae. The needle was advanced in-plane towards the specific target for each technique and a total of four injections were performed using 0.4 ml kg-1 of a dye-lidocaine solution. In phase 3, 10 cadavers received bilateral LQL injections (n = 20). All cadavers were then dissected to evaluate spread of dye. In phase 2, following LQL injections, no dye was observed in undesired locations; however, the dye was noted in the retroperitoneal space (1/2) after TQL injections. In phase 3, the 13th thoracic, first, second, third lumbar nerves, and sympathetic trunk segments were stained in 80%, 95%, 100%, 45% and 35% of the injections, respectively. In conclusion, the LQL technique was feasible, allowing staining of the spinal nerves innervating the cranial abdomen in sheep cadavers. Further studies in live animals are warranted.

Pain quality patterns in delayed onset muscle soreness of the lower back suggest sensitization of fascia rather than muscle afferents: a secondary analysis study

Delayed onset muscle soreness (DOMS) of the lower back is considered a surrogate for acute low back pain (aLBP) in experimental studies. Of note, it is often unquestioningly assumed to be muscle pain. To date, there has not been a study analyzing lumbar DOMS in terms of its pain origin, which was the aim of this study. Sixteen healthy individuals (L-DOMS) were enrolled for the present study and matched to participants from a previous study (n = 16, L-PAIN) who had undergone selective electrical stimulation of the thoracolumbar fascia and the multifidus muscle. DOMS was induced in the lower back of the L-DOMS group using eccentric trunk extensions performed until exhaustion. On subsequent days, pain on palpation (100-mm analogue scale), pressure pain threshold (PPT), and the Pain Sensation Scale (SES) were used to examine the sensory characteristics of DOMS. Pain on palpation showed a significant increase 24 and 48 h after eccentric training, whereas PPT was not affected (p > 0.05). Factor analysis of L-DOMS and L-PAIN sensory descriptors (SES) yielded a stable three-factor solution distinguishing superficial thermal ("heat pain ") from superficial mechanical pain ("sharp pain") and "deep pain." "Heat pain " and "deep pain" in L-DOMS were almost identical to sensory descriptors from electrical stimulation of fascial tissue (L-PAIN, all p > 0.679) but significantly different from muscle pain (all p < 0.029). The differences in sensory description patterns as well as in PPT and self-reported DOMS for palpation pain scores suggest that DOMS has a fascial rather than a muscular origin.

Comparison of thoracolumbar versus non-thoracolumbar osteoporotic vertebral compression fractures in risk factors, vertebral compression degree and pre-hospital back pain

BACKGROUND

Thoracolumbar spine is at high risk of osteoporotic vertebral compression fractures (OVCF). This study aimed to identify the differences in risk factors, vertebral compression degree and back pain characteristics of thoracolumbar OVCF (TL-OVCF) and non-thoracolumbar OVCF (nTL-OVCF).

METHODS

OVCF patients hospitalized in a spine center between June 2016 and October 2020 were retrospectively studied. Demographics, comorbidity, spine trauma, bone mineral density, duration of pre-hospital back pain, extent of vertebral marrow edema, and degree of vertebral compression of patients with nTL-OVCF were summarized and compared to those with TL-OVCF.

RESULTS

A total of 944 patients with acute single-segment OVCF were included. There were 708 (75.0%) TL-OVCF located in T11-L2 and 236 (25.0%) nTL-OVCF in lower lumbar (L3-L5) and middle thoracic (T5-T10) spine. The female-male ratio was 4.1 in nTL-OVCF and differed not significantly from TL-OVCF. The middle thoracic OVCF were older and had higher comorbidity of coronary heart disease (21.3%) and cerebral infarction (36.3%) than TL-OVCF (12.1% and 20.6%). In nTL-OVCF the ratio of apparent spine trauma (44.9%) and pre-hospital back pain ≤ 1 week (47.5%) was lower than in TL-OVCF (66.9% and 62.6%). The T-score value of lumbar spine was - 2.99 ± 1.11, - 3.24 ± 1.14, - 3.05 ± 1.40 in < 70, 70-80, > 80 years old TL-OVCF and differed not significantly from nTL-OVCF. The lower lumbar OVCF had more cranial type of vertebral marrow edema (21.8%) and fewer concurrent lumbodorsal fasciitis (30.8%) than TL-OVCF (16.8% and 43.4%). In TL-OVCF the anterior-posterior vertebral height ratio was lower with back pain for > 4 weeks than for ≤ 1, 1-2, and 2-4 weeks. In nTL-OVCF the degree of vertebral compression differed not significantly with pre-hospital back pain for ≤ 1, 1-2, 2-4, and > 4 weeks.

CONCLUSIONS

Thoracolumbar spine has 2-folds higher risk of OVCF than non-thoracolumbar spine. Non-thoracolumbar OVCF are not associated with female gender, apparent spine trauma or poor bone mineral density, but tend to maintain the degree of vertebral compression and cause longer duration of pre-hospital back pain.

Biomechanical Phenotyping of Chronic Low Back Pain: Protocol for BACPAC

OBJECTIVE

Biomechanics represents the common final output through which all biopsychosocial constructs of back pain must pass, making it a rich target for phenotyping. To exploit this feature, several sites within the NIH Back Pain Consortium (BACPAC) have developed biomechanics measurement and phenotyping tools. The overall aims of this article were to: 1) provide a narrative review of biomechanics as a phenotyping tool; 2) describe the diverse array of tools and outcome measures that exist within BACPAC; and 3) highlight how leveraging these technologies with the other data collected within BACPAC could elucidate the relationship between biomechanics and other metrics used to characterize low back pain (LBP).

METHODS

The narrative review highlights how biomechanical outcomes can discriminate between those with and without LBP, as well as among levels of severity of LBP. It also addresses how biomechanical outcomes track with functional improvements in LBP. Additionally, we present the clinical use case for biomechanical outcome measures that can be met via emerging technologies.

RESULTS

To answer the need for measuring biomechanical performance, our "Results" section describes the spectrum of technologies that have been developed and are being used within BACPAC.

CONCLUSION AND FUTURE DIRECTIONS

The outcome measures collected by these technologies will be an integral part of longitudinal and cross-sectional studies conducted in BACPAC. Linking these measures with other biopsychosocial data collected within BACPAC increases our potential to use biomechanics as a tool for understanding the mechanisms of LBP, phenotyping unique LBP subgroups, and matching these individuals with an appropriate treatment paradigm.

“Long COVID-19” and viral “fibromyalgia-ness”: Suggesting a mechanistic role for fascial myofibroblasts (Nineveh, the shadow is in the fascia)

The coronavirus pandemic has led to a wave of chronic disease cases; “Long COVID-19” is recognized as a new medical entity and resembles “fibromyalgia” which, likewise, lacks a clear mechanism. Observational studies indicate that up to 30%–40% of convalescent COVID-19 patients develop chronic widespread pain and fatigue and fulfill the 2016 diagnostic criteria for “fibromyalgia.” A recent study suggested a theoretical neuro-biomechanical model (coined “Fascial Armoring”) to help explain the pathogenesis and cellular pathway of fibromyalgia, pointing toward mechanical abnormalities in connective tissue and fascia, driven by contractile myo/fibroblasts and altered extracellular matrix remodeling with downstream corresponding neurophysiological aberrations. This may help explain several of fibromyalgia’s manifestations such as pain, distribution of pain, trigger points/tender spots, hyperalgesia, chronic fatigue, cardiovascular abnormalities, metabolic abnormalities, autonomic abnormalities, small fiber neuropathy, various psychosomatic symptoms, lack of obvious inflammation, and silent imaging investigations. Pro-inflammatory and pro-fibrotic pathways provide input into this mechanism via stimulation of proto/myofibroblasts. In this hypothesis and theory paper the theoretical model of Fascial Armoring is presented to help explain the pathogenesis and manifestations of “long COVID-19” as a disease of immuno-rheumo-psycho-neurology. The model is also used to make testable experimental predictions on investigations and predict risk and relieving factors.

Fetal Fascial Reinforcement Development: From "a White Tablet" to a Sculpted Precise Organization by Movement

Simple Summary

Nowadays, the number of studies concerning fasciae is increasing, but few studies focus on fetal fasciae development and there is no study on the retinacula. The latter are fascial reinforcements with a crucial role in proprioception and coordination. We aimed to identify their structural organization by qualitative and quantitative assessments, to establish their role in myofascial development, highlighting their appearance and organization. Our data strongly suggest that the movement models the fascial reinforcements, structuring the fascial system, particularly at the end of the pregnancy.

Abstract

Fasciae have received much attention in recent years due to their important role in proprioception and muscular force transmission, but few studies have focused on fetal fasciae development and there is no study on the retinacula. The latter are fascial reinforcements that play a key role in proprioception and motor coordination. Furthermore, it is still unclear if they are genetically determined or if they are defined by movements, and if they are present during gestation or if they appear only later in the childhood. We aim to identify their structural organization by qualitative and quantitative assessments to establish their role the myofascial development, highlighting their appearance and organization. Samples from the wrist retinacula, posterior forearm, ankle retinacula, anterior leg, iliotibial tract and anterior thigh of six fetus body donors (from 24th to 40th week of gestation) and histological sections were obtained and a gross anatomy dissection was performed. Sections were stained with hematoxylin-eosin to observe their overall structure and measure their thicknesses. Using Weigert Van Gieson, Alcian blue and immunostaining to detect Hyaluronic Acid Binding Protein (HABP), Collagens I and III (Col I and III) were realized to assess the presence of elastic fibers and hyaluronan. This study confirms that the deep fasciae initially do not have organized layers and it is not possible to highlight any reinforcement. The fascial development is different according to the various area: while the deep fascia and the iliotibial tract is already evident by the 27th week, the retinacula begin to be defined only at the end of pregnancy, and their complete maturation will probably be reached only after birth. These findings suggest that the movement models the retinacula, structuring the fascial system, in particular at the end of pregnancy and in the first months of life. The fasciae can be imagined, initially, as “white tablets” composed of few elastic fibers, abundant collagens and HA, on which various forces, u movements, loads and gravity, “write their history”.

Dose-Dependent Pain and Pain Radiation after Chemical Stimulation of the Thoracolumbar Fascia and Multifidus Muscle: A Single-Blinded, Cross-Over Study Revealing a Higher Impact of Fascia Stimulation

Acute low back pain can be experimentally induced by injections of hypertonic saline into deep tissues of the back, such as fascia and muscle. The current study investigated the dose-dependency of peak-pain and spatial extent of concomitant radiating pain following 50, 200 and 800 μL bolus injections of hypertonic saline (5.8%) into the thoracolumbar fascia and multifidus muscle, since data on dose-dependency is lacking in humans. Sixteen healthy subjects rated (11 female, 5 male; 23.3 ± 3.1 years, mean ± SD) intensity and spatial extent of pain. Injections into the fascia resulted in significantly higher peak-pain (+86%, p < 0.001), longer pain durations (p < 0.05), and larger pain areas (+65%, p < 0.02) and were less variable than intramuscular injections. Peak-pain ratings and pain areas were 2−3-fold higher/larger for 200 μL vs. 50 μL. In contrast, peak pain increased only marginally at 800 μL by additional 20%, while pain areas did not increase further at all in both, fascia and muscle. Thus, higher injection volumes did also not compensate the lower sensitivity of muscle. Peak-pain ratings and pain areas correlated between fascia and muscle (r = 0.530, p < 0.001 and r = 0.337, p < 0.02, respectively). Peak-pain ratings and pain areas correlated overall (r = 0.490, p < 0.0001), but a weak correlation remained when the impact of between-tissue differences and different injection volumes were singled out (partial r = 0.261, p < 0.01). This study shows dose-dependent pain responses of deep tissues where an injection volume of 200 μL of hypertonic saline is deemed an adequate stimulus for tissue differentiation. We suggest that pain radiation is not simply an effect of increased peripheral input but may afford an individual disposition for the pain radiation response. Substantially higher pain-sensitivity and wider pain areas support fascia as an important contributor to non-specific low back pain.